The present invention relates generally to a vibratory compactor, and more particularly to a vibratory compactor of the type that is partly or wholely immersed in flowable concrete or the like to effect compacting of the same.
Vibratory compactors of this type are already known. They usually have a substantially tubular housing having a free end onto which, according to one prior-art construction, a replaceable steel cap is threadedly mounted. This free end with the steel cap is plunged into flowable concrete or other material to be compacted, and an electromotor is energized which effects rotation of an imbalanced mass within the tubular housing. The imbalance of the rotating mass creates vibrations which are transmitted to the housing and from there to the concrete or like material, so that the material thereby becomes compacted. Due to the contact with the substance of the concrete or other material, there is a substantial amount of wear on such compactors. It was assumed that this wear was primarily concentrated at the end cap which, according to the aforementioned prior-art proposal, was made replaceable so that it could be replaced with a new one when it had become excessively worn.
However, it has since been found that the end cap is by no means the only portion of the compactor housing that is subject to very drastic and rapid wear. Instead, the tubular housing itself is also subject to wear, and this wear is particularly strong if the concrete or other material to be compacted contains a large proportion of fine gravel or stone splinters. It has been found that particularly strong wear will occur in the front region of the housing, that is the region which is the leading one when the housing is dipped into the mass to be compacted, in which region the rotating imbalanced mass is mounted in the interior of the housing. Of course, it is self-evidently possible to decrease the wear by decreasing the amount of vibrations that are caused in operation of the device, but on the other hand it is equally evident that this results in a decrease of the operational effectiveness of the device. Another approach would be to replace the housing whenever it becomes worn, but since the housing must be made of expensive highly ware-resistant material to be able to withstand the abrasive effect for a reasonable period of time, this becomes very expensive and in the long run is economically unacceptable.